As is well known, a loudspeaker comprises a frame or "basket" which supports the rim of a speaker cone of light, fairly rigid material such as stiff paper, the cone terminating near its apex by a cylindrical "voice coil", through which the audio frequency energization to the speaker passes. The basket also supports a magnet assembly to create a fixed radial magnetic field in which the voice coil can move axially because of the resilience of the speaker cone. Magnet assemblies typically employ ceramic magnets although some use alnico magnets. Many magnet assemblies employ a flat front plate which forms part of the assembly and serves as the surface to which the basket is attached, as well as completing the magnetic path outside the voice coil, which it is apertured to pass. In the prior art, numerous methods were employed to secure the front plate to the basket, including welding or bolting the two parts together or forming staking studs in the front plate and piercing the basket with corresponding holes for accepting the studs, and then staking the studs thereby, bonding the two parts to each other.
All of these prior methods had significant drawbacks which resulted in increased cost of production. Bolting, for example, requires expensive drilling and tapping of the front plate. Stud staking requires specially designed front plates and the extra step of staking. In the welding process, alignment of the basket and front plate is difficult and quality control is a problem. These methods have also proved unsatisfactory for use in attaching a large magnet assembly to a small basket due to the lack of available surface area on the basket necessary to weld, bolt or stud stake.